1. Field of the Invention
The present invention relates to an ink ejecting head of a thermal system for use in an inkjet printer head or the like, and an ink ejecting apparatus such as an inkjet printer including the ink ejecting head. More specifically, the present invention relates to a technique for realizing a liquid supply structure with little ejection non-uniformity.
2. Description of the Related Art
As an example of liquid ejecting heads for use in a liquid ejecting apparatus such as an inkjet printer, there is known a thermal system that utilizes the expansion and contraction of generated bubbles.
In such a thermal system, heater elements are provided on a semiconductor substrate, bubbles are generated in the liquid inside a liquid chamber by these heater elements, and liquid is ejected in the form of droplets from nozzles arranged on the heater elements to be impacted on a recording medium or the like.
FIG. 13 is a perspective exterior view showing a liquid ejecting head 1 (hereinafter, simply referred to as “head 1”) of this type according to the related art. In FIG. 13, a nozzle sheet 17, which is provided on a barrier layer 3, is shown in an exploded state.
FIG. 14 is a sectional view showing the channel structure of the head 1 shown in FIG. 1. It should be noted that a channel structure of this type employed in a liquid ejecting apparatus is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2003-136737.
In FIGS. 13 and 14, a plurality of heater elements 12 are arranged on a semiconductor substrate 11. Further, the barrier layer 3 and the nozzle sheet (nozzle layer) 17 are laminated in order on the semiconductor substrate 11. Herein, an assembly in which the heater elements 12 are formed on the semiconductor substrate 11, with the barrier 3 being formed above the heater elements 12, is referred to as a head chip 1a. Further, an assembly with nozzles 18 (nozzle sheet 17) formed on the head chip 1a is referred to as the head 1.
The nozzle sheet 17 has the nozzles 18 arranged such that the nozzles (holes for ejecting droplets) 18 are located on the respective heater elements 12. Further, the barrier layer 3 provided on the semiconductor substrate 11 is interposed between the heater elements 12 and the nozzles 18, thus forming liquid chambers 3a between the portion above the heater elements 12 and the nozzles 18.
As shown in FIG. 13, the barrier layer 3 is formed in a substantially comb-tooth like configuration so as to surround three sides of each heater element 12, thereby forming the liquid chamber 3a of which only one side is open. This opening portion forms an individual channel 3d, which communicates with a common channel 23.
Further, the heater elements 12 are arrayed in proximity to one side of the semiconductor substrate 11. Further, in FIG. 14, a dummy chip D is arranged on the left side of the semiconductor substrate 11 (head chip 1a), so the common channel 23 is formed by one side surface of the semiconductor substrate 11 (head chip 1a) and one side surface of the dummy chip D. It should be noted that any kind of member may be used instead of the dummy chip D as long as the common channel 23 can be formed.
Further, as shown in FIG. 14, a channel plate 22 is arranged on the surface of the semiconductor substrate 11 opposite to the surface on which the heater elements 12 are provided. As shown in FIG. 14, an ink supply port 22a and a supply channel (common channel) 24, which is substantially recessed in cross section so as to communicate with the ink supply port 22a, are formed in the channel plate 22. The supply channel 24 and the common channel 23 communicate with each other.
Accordingly, ink is fed from the ink supply port 22a to the supply channel 24 and the common channel 23, and passes through the individual channel 3d to enter the liquid chamber 3a. Then, as the heater element 12 is heated, bubbles are generated on the heater element 12 inside the liquid chamber 3a. The flight force exerted at the time of this bubble generation causes a part of the liquid in the liquid chamber 3a to be ejected in the form of (ink) droplets from the nozzle 18.
It should be noted that in FIGS. 13 and 14, for the ease of understanding, the actual configurations are ignored, and the configurations are depicted in an exaggerated manner. For instance, the thickness of the semiconductor substrate 11 is about 600 to 650 μm, and the thickness of the nozzle sheet 17 or barrier layer 3 is about 10 to 20 μm.
Further, examples of the method of manufacturing the above-mentioned head 1 include a first (chip mount) method in which the head chip 1a manufactured through the semiconductor process is bonded onto the nozzle sheet 17 manufactured through a separate process, and a second method (on chip nozzle: OCN) in which the portion of the nozzles 18 is also formed integrally on the semiconductor substrate 11.